The present invention relates, in general, to the field of data transmission and to a method of transmitting data from a central station to a track-bound vehicle.
Nothing in the following discussion of the state of the art is to be construed as an admission of prior art.
Data between a track-bound vehicle and a central station is transmitted heretofore by so-called intermittent train control (intermittent ATC) or continuous automatic train control (continuous ATC). Intermittent automatic train control involves a transmission of data between the central station and a track-bound vehicle along a track at selected points with limited range. However, no data transmission is possible at locations along the track between individual points.
Continuous ATC provides a data transmission along the entire track between the railway vehicle and the central station. European Pat. No. EP 0 534 577 describes, for example, a continuous ATC, whereby a communication is established via track-side transmitting and receiving devices which are operatively connected with on-vehicle transmitting and receiving devices. Several track-side transmitting and receiving devices are hereby operated by a control computer which is in communication with a central station, for example a signal box or operations control station. In the event, the control computer crashes during operation, any communication between the track-side transmitting and receiving devices and the on-vehicle transmitting and receiving devices is interrupted. Trains that are affected by this breakdown are halted by the safety system, resulting in downtimes and delays. One approach to prevent such delays involves a doubling of all components, i.e. of the track-side transmitting and receiving devices as well as the associated control computers, so that a breakdown of one component can be compensated by the availability of the backup component.
It would be desirable and advantageous to provide an improved data transmission system to obviate prior art shortcomings and to maintain operation in a simple and yet reliable manner, even when a control computer crashes.